1. Field of the Invention
The present invention relates to an apparatus useful for the formation of ethylene oxide, or more particularly for ethylene oxide reabsorption and carbon dioxide stripping on a commercial scale. This apparatus finds particular use as an improved single column ethylene oxide reabsorber/stripper vessel. According to this invention, the steps of ethylene oxide re-absorption and carbon dioxide stripping, which normally are carried out in separate vessels, are carried out in a single column vessel having an internal dividing baffle. The apparatus may also be used for other chemical processing systems that require reabsorption and stripping.
2. Description of the Related Art
The oxidation of ethylene to form ethylene oxide and the various recovery procedures associated therewith as well as additional conversion of ethylene oxide to ethylene glycol are well known and widely practiced commercially. See, for example, U.S. Pat. Nos. 5,945,551, 6,184,175, 5,646,087, and 6,533,843.
Typically, an ethylene oxide product is absorbed from the oxidation reaction gases in an aqueous absorbent liquid to form a dilute ethylene oxide solution. The ethylene oxide is stripped from the dilute aqueous solution and, the stripper overhead is sent to a condenser where the bulk of the water is condensed and separated. The ethylene oxide vapor stream from the stripper overhead concentrated in ethylene oxide is passed to a re-absorber where ethylene oxide is re-absorbed in water and thus separated from inerts which are vented. The ethylene oxide re-absorber solution, which also contains substantial amounts of dissolved carbon dioxide, is sent to a glycol feed stripper where carbon dioxide is separated by steam/inert gas stripping. Such conventional operation is illustrated in the attached FIG. 1.
The invention provides an improved apparatus wherein the functions of both a conventional re-absorber column and glycol feed stripper column are combined and carried out in a single column, which is divided by an internal baffle into separate reabsorption and stripping sections.
Such a combined single-column vessel offers several economic advantages, including simplification of industrial operations, and reduction in required floor area necessary for such equipment. Furthermore, since exposure of ethylene oxide to external fire is a significant safety hazard, a reduction in equipment would lessen the surface area of equipment requiring fireproofing, reduce potential exposure to fire, and improve the overall safety of the plant.